This invention relates to real-time ultrasonic interrogating systems, and, more particularly, to circuitry for exciting a transducer and for receiving echos in an ultrasonic interrogating system which is for example useful in the biological investigation arts.
A system environment in which the circuitry of the present invention has found significant utility is described in my copending patent application Ser. No. 389,958, for "Ultrasonic Cross-Sectional Imaging System", filed Aug. 20, 1973, and assigned to a common assignee herewith, now Pat. No. 3,881,466. The ultrasonic imaging system disclosed therein is characterized by the use of an array of relatively narrow transducers which are excited in groups according to a predetermined sequence in order to achieve improved resolution by an overlapping ultrasonic scanning pattern.
The most advanced known prior art real-time ultrasonic imaging system for carrying out biological investigations is disclosed in an article by Bom et al, published in the November, 1971, issue of "Bio-Medical Engineering", pages 500-503, 508, and entitled "Ultrasonic Viewer for Cross-Sectional Analyses of Moving Cardiac Structures". The Bom et al apparatus utilizes a linear array of twenty relatively large transducers excited sequentially on an individual basis. Twenty power transistors and twenty preamplifiers are necessary to achieve transducer excitation and echo detection, and the electronic circuits and transducers are coupled by twenty separate coaxial cables. Each transducer is connected in parallel with a tuning inductor, which must be provided to damp unwanted low frequency cross-mode vibrations.
There are two basic disadvantages to the prior art apparatus as exemplified by the Bom et al system. First, the inordinate inherent clumsiness and unreliability are a serious drawback. Second, the necessity for providing twenty complete discrete electronic channels exhibiting high performance characteristics inevitably results in undesirably high costs. The present invention is directed to overcoming both these disadvantages while further affording superior performance.